Method of hot-filling a plastic, wide-mouth, blow-molded container having a multi-functional base

ABSTRACT

A container can have a body with an integrally formed base attached to the body. The base includes a concave annular wall extending from the container sidewall to a standing surface, and an inner wall extending from the standing surface to a substantially flat inner annular wall. The inner annular wall is recessed in the base and is substantially perpendicular to the container sidewall. The inner annular wall includes a centrally located dimple. The dimple includes a plurality of spaced apart and radially extending indented ribs. One or more of the ribs extend radially into a brace that tapers to meet the inner annular wall.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a division of U.S. patent application Ser.No. 10/851,083 (U.S. Pat. Pub. No. 2004/0211746) filed May 24, 2004, nowU.S. Pat. No. 7,543,713 which is a continuation-in-part of U.S. patentapplication Ser. No. 10/444,616 (U.S. Pat. Pub. No. 2003/0196926)(abandoned) filed on May 23, 2003, which is a continuation-in-part ofU.S. patent application Ser. No. 10/124,734 filed on Apr. 17, 2002, nowU.S. Pat. No. 6,612,451, which claims the benefit of priority of U.S.Provisional Patent Application No. 60/284,795 filed on Apr. 19, 2001.Additionally, PCT application PCT/US2004/016405 filed May 24, 2004 alsoclaims priority to U.S. patent application Ser. No. 10/444,616 (U.S.Pat. Pub. No. 2003/0196926) (abandoned). The contents of each of theforegoing are incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to a base for a wide mouth blow-moldedplastic container, and more particularly, the present invention relatesto a multi-functional base structure which enables use of the containerin hot-fill, as well as pasteurization/retort processing.

BACKGROUND OF THE INVENTION

Plastic blow-molded containers, particularly those molded of PET, havebeen utilized in hot fill applications where the container is filledwith a liquid product heated to a temperature in excess of 180° F. (82°C.), capped immediately after filling, and allowed to cool to ambienttemperatures. Plastic blow-molded containers have also been utilized inpasteurization and retort processes, where a filled and sealed containeris subjected to thermal processing and is then cooled to ambienttemperatures. Pasteurization and retort methods are frequently used forsterilizing solid or semi-solid food products, e.g., pickles andsauerkraut, which may be packed into the container along with a liquidat a temperature less than 82° C. (180° F.) and then heated, or theproduct placed in the container that is then filled with liquid, whichmay have been previously heated, and the entire contents subsequentlyheated to a higher temperature. Pasteurization and retort differ fromhot-fill processing by including heating the contents of a filledcontainer to a specified temperature, typically greater than 93° C.(200° F.), until the contents reach a specified temperature, for example80° C. (175° F.), for a predetermined length of time. Retort processesalso involve applying overpressure to the container. In each of thesecases, the plastic containers are typically provided with vacuumabsorption panels to accommodate volumetric changes in the container asthe contents of the sealed container are heated and/or as the contentscool within the sealed container.

U.S. Pat. No. 6,439,413 issued to Prevot et al. and assigned to GrahamPackaging Company, L.P. discloses a hot-fillable and retortable plasticwide-mouth blow-molded container having a sidewall with a pair of flexpanels.

Co-pending U.S. patent application Ser. No. 10/129,885 filed on May 10,2002 is the U.S. national phase of International Application No.PCT/USOO/31834 is assigned to Graham Packaging Company, L.P., anddiscloses a pasteurizable wide-mouth container having a novel base.

Other plastic wide-mouth containers having paneled sidewalls aredisclosed in U.S. Pat. Nos. 5,887,739 issued to Prevot et al.; 5,261,544issued to Weaver, Jr.; and 5,092,474 issued to Leigner. A pasteurizableplastic container having paneled sidewalls and a narrow neck finish isdisclosed by U.S. Pat. No. 5,908,128 issued to Krislmakumar et al.

Containers having non-paneled sidewalls and yieldable endwall structuresare disclosed in U.S. Pat. Nos. 4,642,968, 4,667,454 and 4,880,129issued to McHenry et al.; 5,217,737 issued to Gygax et al.; 5,234,126issued to Jonas et al.; 4,381,061 issued to Cerny et al.; 4,125,632issued to Vosti et al.; and 3,409,167 issued to Blanchard. The abovecited U.S. patents disclose containers having various base structures.

The structure of a so-called footed base is disclosed, in general, inU.S. Pat. Nos. 4,355,728 issued to Yoshino et al., 5,713,480 issued toPetre et al., 3,727,783 issued to Carmichael, 4,318,489 issued to Snyderet al., 5,133,468 issued to Brunson et al., 5,024,340 issued toAlberghini et al., 3,935,955 issued to Das, 4,892,205, 4,867,323 and Re.35,140 issued to Powers et al., and 5,785,197 issued to Slat.

U.S. Pat. No. 4,321,483 issued to Dechenne et al. discloses a basehaving slightly angled annular surface and a central conical projection;and U.S. Pat. No. 4,386,701 issued to Galer discloses a blow moldedplastic drum having a base which is designed to stack efficiently withthe lid of a like drum.

Plastic containers, including those described in the above-mentionedreferences, containers, including containers designed for use inhot-fill processing. There remains a need to provide plastic containersthat can withstand the rigors of pasteurization and retort processing inorder to take advantage of the cost savings that can be realized throughmanufacture and recycling. The lighter weight of plastic containers ascompared to glass can also advantageously reduce shipping costs.

Published International Application No. WO 02/02418 describes acontainer with a base that can be capable of withstanding the rigors ofthe pasteurization process. The base includes a large push up sectionformed with a sharp transition to the container sidewall. The base alsomust be heat set to a relatively high crystallinity.

While the above referenced containers and base structures may functionsatisfactorily for their intended purposes, there is a need for aplastic, wide-mouth, blow-molded container which is particularly suitedfor packaging a variety of viscous and other food products and which hasa novel base structure that enables the container to be utilized inhot-fill, pasteurization and retort processes. The base structure shouldbe capable of accommodating increased internal pressure experiencedduring pasteurization; capable of accommodating vacuum formed in thesealed container during cool down; and capable of resisting unwantedinversion, ovalization or like deformation. A container capable ofefficient stacking with like containers is also desirable.

SUMMARY OF THE INVENTION

With the foregoing in mind, an object of the present invention is toprovide a commercially satisfactory wide-mouth blow-molded containerthat can be utilized in hot-fill applications, as well as forpasteurization or retort applications used in for packaging fluent,viscous and solid food products.

Another object of the present invention is to provide a base structurecapable of accommodating an increase in internal container pressure whenthe sealed container is subjected to thermal treatment, and capable ofaccommodating vacuum during cool down.

Still another object of the present invention is to provide ahot-fillable and pasteurizable container having a base whichaccommodates changes in internal pressure and volume and which resistsunwanted inversion and other deformation.

A further object of the present invention is to provide a structure fora wide-mouth plastic container which can be efficiently stacked, one ontop of the other, with like containers and which can be produced bymeans of high speed manufacturing equipment in an economical manner thatensures consistent quality and performance.

More specifically, the present invention provides a blow molded plasticcontainer having a base with a continuous or discontinuous concave outerannular wall having an outer portion and an inner portion forming astanding ring therebetween. The base also includes an inner annular wallthat extends within the outer annular wall and above the standing ring.The inner periphery of the inner annular wall is made of blow moldedplastic material that is heat-set and biaxially-oriented and connects toan anti-inverting central dimple. Functionally, the inner annular wallis capable of flexing upwardly and downwardly in response to variationsin pressures in a filled and sealed container without undergoingunwanted permanent deformation. In addition, preferably a shoulderextends radially inward on the inner portion of the outer annular wallabove a level of the standing ring to facilitate vertical stacking ofcontainers having like bases.

In a particular embodiment, the container includes a body having anintegrally formed base that includes a concave annular wall extendingfrom a sidewall of the container to a standing surface, an inner wallthat is substantially perpendicular to the sidewall and extends from thestanding surface to a substantially flat inner annular wall. The concaveannular wall can be continuous. A dimple is centrally located within theinner annular wall and includes a plurality of spaced apart radiallyextending indented ribs. Each rib has a brace that extends radially fromthe dimple and tapers to meet the inner annular wall. The ribs can alsoinclude a rib wall; and a brace ledge tapering from the rib wall to theinner annular wall, a rib wall; and a brace ledge tapering from said ribwall to the inner annular wall. A brace sidewall extending from saidbrace ledge to said inner annular wall.

The container can be made of a blow molded plastic material, and thedegree of crystallinity of the plastic material in the base is greaterthan the degree of crystallinity of the plastic material in thesidewall. The degree crystallinity in the base can be greater than 20%an can be less than 30%. The sidewall diameter can be no more than 50%greater than the inner diameter of the standing surface.

The inner annular wall of the base is adapted to flex upwardly anddownwardly in response to variations in pressures within the container,when capped and filled, without undergoing unwanted permanentdeformation.

The invention is also a method of improving resistance to basedeformation in a blow molded plastic container comprising forming aconcave annular wall extending from an extremity of the base to astanding surface, forming an inner wall extending from the standingsurface to a substantially flat inner annular wall that is substantiallyperpendicular to the sidewall; and forming a centrally located dimplewithin the inner annular wall and a plurality of spaced apart radiallyextending indented ribs, each of the ribs comprising a brace extendingradially from the dimple and tapering to meet the inner annular wall.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the presentinvention should become apparent from the following description whentaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a container having a base according toan embodiment of the present invention;

FIG. 2 is an elevational view of the container illustrated in FIG. 1;

FIG. 3 is bottom plan view of the base illustrated in FIG. 1;

FIG. 4 is a cross-sectional view of the base taken along line IV-IV ofFIG. 3;

FIG. 5 is a cross-sectional view of the base taken along line V-V ofFIG. 2 and illustrates a pair of containers in a stacked arrangement;

FIG. 6 is a perspective view of a container having a base according toanother embodiment of the invention;

FIG. 7 is a bottom view of the base according to the embodimentillustrated in FIG. 6;

FIG. 8 is a cross-section of the base of FIG. 6 taken along theVIII-VIII line of FIG. 7;

FIG. 9 is a cross-section of the base of FIG. 6 taken along the lineIX-IX of FIG. 7;

FIG. 10 is a perspective view of a container having a base embodying thepresent invention;

FIG. 11 is an elevational view of the container illustrated in FIG. 10;

FIG. 12 is bottom plan view of the base illustrated in FIG. 10;

FIG. 13 is a cross-sectional view of the base taken along line 4-4 ofFIG. 12; and

FIG. 14 is a cross-sectional view of the base taken along line 5-5 ofFIG. 11 and illustrates a pair of containers in a stacked arrangement.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the present invention is illustrated in FIGS. 1-5 ascontainer 100. Container 100 has a base 112, a tubular sidewall 114, anda wide-mouth threaded finish 116 which projects from the upper end ofthe sidewall 114 via a shoulder 118. In the illustrated embodiment,upper and lower label bumpers, 120 and 122, are located adjacent theshoulder 118 and base 112, respectfully, and outline a substantiallycylindrical label area 124 on the sidewall 114. Containers according tothe invention can have cross-sectional shapes other than circular. Inaddition, the sidewall 114 can have a series of circumferential grooves126 which reinforce the sidewall 114 and resist paneling, dents andother unwanted deformation of the sidewall 114.

The container 100 is multi-functional since it can be utilized inhot-fill as well as pasteurization and retort processing. To accomplishthis objective, the base 112 has a structure which is capable ofaccommodating elevated internal container pressure experienced duringpasteurization or retort processing, and which is capable ofaccommodating reduced container volume and pressure experienced uponcool down of a filled and sealed container after hot-fill,pasteurization or retort processing. To this end, the base 112 can flexdownwardly in a controlled manner and to a desired extent when pressurewithin the filled and sealed container is elevated, and the base 112 canflex upwardly in a controlled manner and to a desired extent when avacuum develops within the filled and sealed container.

Structurally, the base 112 includes a concave outer annular wall 128that is either continuous or discontinuous. FIGS. 1-5 illustrate anembodiment of the base 112 having a discontinuous concave outer annularwall 128 that provides a plurality of spaced-apart, arcuate supports 130adjacent the outer periphery 132 of the base 112. Each support 130 hasan outer wall portion 134 that extends upwardly toward the lower labelbumper 122 and an inner wall portion 136 that extends upwardly andinwardly into the remaining base structure as will be discussed. Astanding surface 138 is formed at the juncture of each outer and innerwall portions, 134 and 136, thereby forming a discontinuous support ringof the container 100. FIGS. 6-9 illustrate an embodiment of a base 212having a continuous concave outer annular wall 228 that forms acontinuous standing surface 238, as described more fully below.

An inner annular wall 140 of base 112 extends within the concave outerannular wall 128. The inner annular wall 140 has an outer periphery 142and an inner periphery 144. The outer periphery 142 of the inner annularwall 140 merges with the inner wall portion 136 of each of the supports130 and, in the illustrated embodiment, with a plurality ofspaced-apart, horizontally-disposed, radial webs 146 located adjacentthe outer periphery 132 of the base 112. Each of the webs 146 extendsbetween the supports 130 and connects to the container sidewall 114 atan elevation above the horizontal plane “P” extending through thestanding surface 138. In an embodiment of the present invention in whichthe concave outer annular wall 128 is continuous, webs 146 are notprovided. The inner periphery 144 of the inner annular wall 140 mergesinto an anti-inverting central dimple 148.

The inner annular wall 140 functions as a flex panel. To this end, whenthe internal pressure increases within a filled and sealed container,the inner annular wall 140 flexes downwardly to accommodate theincreased pressure and to prevent the sidewall 114 of the container 100from undergoing unwanted permanent distortion. In addition, the innerannular wall 140 flexes upwardly to relieve vacuum when the contents ofa hot filled and capped container, or a filled, capped and subsequentlypasteurized container, cool to ambient. Thus, when the sealed containerand contents cool to ambient temperature, the sidewall 114 issubstantially unchanged from its as-formed shape and is capable ofneatly supporting a wrap-around label without unwanted voids or the likebeneath the label. In addition, the sidewall 114 resists ovalization andthe base 112 provides a level seating surface which is not subject torocking or the like.

The base 112 of container 100 is specifically designed to provideflexural movement. Increasing flexure of the base 112 is accomplished byproviding a larger circular flat between the dimple 148 and the arcuatesupports 130. Thus, the inner annular wall 140 of container 100 isrelatively large compared to other containers of a similar size. To thisend, the diameter, size, or extent of the central dimple 148 is reducedand the inner diameter of the arcuate supports 130 is increased relativeto prior art container.

The relatively large flat surface provided by inner annular wall 140provides greater flexure; however, it can also be more prone to “rollout”, i.e. becoming permanently deformed in an outwardly projectingposition when its contents are hot-filled or heated at relatively hightemperatures, such as those encountered during pasteurization or retortprocessing. This is because an amorphous ring of material is created atthe interconnection of the inner periphery 144 of the inner annular wall140 and the dimple 148 due to the reduced size of the dimple 148. Thisring of un oriented, non heat-set material provides a weakened area thatpermits the base to “roll out” when filled and sealed with contents athigh temperatures.

The base 112 of the present invention overcomes the “roll out” problemby providing a series of spaced-apart, radially-extending, hollow,indented ribs 150 in the dimple 148 where the inner periphery 144 of theinner annular wall 140 interconnects to the central dimple 148. Thestructure provided by the ribs 150 causes the material in this region tobe stretched during blow molding of the container 100 so that the ringof material adjacent the interconnection of the dimple 148 and innerannular wall 140 is both heat-set and the extent of biaxial orientationincreased to structurally reinforce the base and prevent “roll out” ofthe base 112. If desired, the dimple 148 can be indented to a givenextent into the container 100 to provide additional stretching, and thetotal number of ribs 150 can be three or more, such as six asillustrated in FIG. 1. In addition, the shape and size of the ribs canvary as long as the blow molded plastic material forming the base at theinterconnection of the dimple 148 and inner annular wall 140 hassufficiently increased biaxial orientation and is heat-set by heatedsurfaces of a blow mold.

Thus, the inner annular wall 140 flexes downwardly when the container isfilled, capped and subjected to an increase in pressure within thecontainer. However, complete inversion and failure is prevented by thereinforcement ribs 150 formed in the dimple 148, which travel with theinner annular wall 140. The ribs 150 and dimple 148 maintain asubstantially constant shape regardless of the internal pressureexperienced within the container, due to the increase in density andstiffness resulting from the increased orientation.

Another feature of the base 112 of the present invention is that eachinner wall portion 136 of the arcuate supports 130 can have an arcuateshoulder, or support ridge, 156 formed therein and spaced in elevationfrom both the support surfaces 138 and the inner annular wall 140 tofacilitate vertical stacking of like containers 100. For example, asillustrated FIG. 5, an upper container 100 a can be stacked on a lowercontainer 100 b. The support ridge 156 in the base 112 a of the uppercontainer 100 a seats on the outer edge 158 of the upper surface 160 ofthe lid 162 of the lower container 100 b such that the horizontal plane“P_(a)” extending through the standing surfaces 138 a of the uppercontainer 100 a extends a spaced distance beneath the top surface 160 ofthe lid 162 of the lower container 100 b.

By way of example, and not by way of limitation, the container 100according to the present invention preferably has a height “H” of about5.8 inches, a container outermost diameter “D” of about 4.2 inches, andcan contain a capacity of about 32 fluid ounces. The discontinuousstanding ring formed by the standing surfaces 38 has a diameter of about3.7 inches, and the inner annular wall 140 of the base 112 has an innerperiphery 144 with a diameter of less than about 1.25 inches and anouter periphery 142 with a diameter of at least about 2.5 inches. Theradial webs 146 are uniformly spaced apart and separate each support 130such that each support 130 is at least about 0.8 radians. In addition,each support 130 has a larger arcuate extent than that of each radialweb 146.

FIGS. 6-9 illustrate a second embodiment of a base 212 that may be usedon a container 200 according to the present invention. Other than thebase 212, the container 200 can be the same as or different fromcontainer 100. Accordingly, the last two digits in reference numeralsused to designate features of the container 200 are the same as thereference numerals that are used to designate the related features incontainer 100. For example, the container 200 can include a threadedfinish 216 that can be the same as the threaded finish 116 of the firstembodiment, and can accommodate a closure 262 having complementarythreads. Similarly, the shoulder 218, upper bumper 220, circumferentialgrooves 226, label area 224, and sidewall 214 can be structurallysimilar to the corresponding features of the first embodiment.

The second embodiment of the base 212 includes a continuous concaveouter annular sidewall 228. The outer portion 228 of the annularsidewall curves from the sidewall 214 toward the center of the container200 to form a continuous standing surface 238. The standing surface 238is formed as a continuous, circular surface. Further, the transitionfrom the outer annular sidewall 228 to the standing surface 238 isgradual and continuous. An inner portion 236 of the outer annularsidewall extends from the standing surface 238 to a substantially flatinner annular wall 240. The outer periphery 242 of the inner annularwall 240 forms a continuous ring around the inner annular wall 240.

Approximately centrally located on the inner annular wall 240 is adimple 248. Extending outwardly from the dimple 248 are a series of ribs250. The dimple 248 of this embodiment can be substantially the samesize as the dimple 148 in the first embodiment 100, or can be slightlylarger. The ribs 250 of the second embodiment extend outwardly to form aseries of radially placed braces 270, which taper to an elevation thatmeets the flat inner annular wall 240 before, near, or the outerperiphery 242 of the inner annular wall. In the illustrated embodiment,the ribs 250 first extend outward from the dimple at a similar depth tothe inner portion 272 of the dimple to a rib wall 274, where there is arelatively abrupt change in depth toward the inner annular wall 240. Therib wall 274 extends up to a brace ledge 276 which slopes towards thesurface of the inner annular wall 240. The brace ledge 276 can meet thesurface of the inner annular wall 240 at or before the outer periphery242. The sidewall of the brace 278 extends upward from the brace ledge276 to the surface of the inner annular wall 240. The brace sidewall 278meets the inner annular wall 240 at a periphery of the brace 270. Thesidewall of the brace 278 can be substantially perpendicular to theinner annular wall 240 and the brace ledge 276.

The inner annular wall 240 in base 212 flexes in a manner analogous tothe inner annular wall 140 of base 112. The radially spaced braces 270further control flexure of the annular wall 240 in response to thereduced pressures that occur when the container cools down duringhot-fill processing, and the reduced and increased pressures that occurduring pasteurization and retort processing. The presence of the braces270 allows greater flexure of the inner annular wall 240 within theconcave outer annular wall 228 without allowing permanent deformation ofthe base. In addition, the presence of a continuous outer annular wall228 is useful during rigorous pasteurization or retort conditions. Undersuch conditions, a discontinuous outer sidewall that has feet can have atendency for the feet to pull in, causing the lower bumper to move intoa square shape. By having a continuous standing surface 238 and acontinuous outer annular sidewall 228, this tendency is reduced.Further, the presence of a continuous standing surface 238 alleviatesany tendency for excessive base rollout.

The base structure described herein is illustrated without a supportridge 156 (see FIGS. 1-5) for stacking of containers. Such a ridge orshoulder can, however, be readily incorporated into a base 242 accordingto this second embodiment of the invention.

The base 212 according to the present invention is preferablycrystallized to some extent as previously described in the firstembodiment. Some degree of crystallinity and biaxial orientation isachieved normally during the blow molding process. Crystallization canalso be promoted through heat setting of the container. For example, thewalls and base of the mold can be held at an elevated temperature topromote crystallization. When the container is heat set at a temperatureof about 180° F., the container sidewalls, base, dome, and threads canbe typically crystallized to about 20%. This degree of crystallinity istypical for a blow molding process and does not represent a significantamount of heat setting or increased crystallinity or orientation, ascompared with a typically prepared container. However, the properties ofthe base of the present invention can be advantageously enhanced by heatsetting the container, and particularly the base, at ever highertemperatures. Such temperatures can be, for example, greater than 250°F. and can be 325° F. or even higher. When these elevated heat settemperatures are utilized, crystallinity can be increased to greaterthan 20% or 25% or more. One drawback of increasing crystallinity andbiaxial orientation in a plastic container is that this processintroduces opacity into the normally clear material. However, unlikebases in prior art containers designed for use in pasteurization andretort processes, which can require a crystallinity of 30% or more,utilizing crystallinities of as low as 22-25% with a base structureaccording to the present invention can achieve significant structuralintegrity, while maintaining the substantial clarity of a base that ispreferred by manufacturers, packagers and consumers of such pasteurizedcommodities. Crystallinities of 30% or greater that are frequentlyutilized in prior container to achieve significant structural integritycan cause undesirable opacity in the base region.

Bases formed with configurations according to the present inventionprovide a more appealing structure to consumers, packagers andmanufacturers for other reasons, as well. For example, when switchingfrom the use of glass to plastic in packaging such pasteurizablecommodities, design changes cause undesirable changes in the internalcontainer configuration. Typically, in order to withstand the rigors ofpasteurization or retort processing, prior containers have included abase formed with a large central push-up, as is used in typical plasticcontainers used in hot-fill processes. This push-up limits the volume ofmaterial that can be placed in the container in the internal regionbetween the push-up and the sidewalls. This can be particularlyproblematic when solid products, for example, pickles, are packaged. Thepresence of narrow channels which are formed between the sidewall andlarge base push-up in the internal space of a typical blow moldedcontainer, can limit the volume into which solid materials can beplaced. That is, such designs create dead space within the containerthat can be filled by liquid, but not by the solid product. Intraditional glass containers, a relatively flat bottom can be formedwhich allows solids to be packed throughout the vertical and radialextent of the container. Prior art plastic containers that have beenutilized to withstand the pasteurization and retort conditions have usedsimilar internal geometry, which creates dead space.

According to the present invention, and particularly according to thesecond embodiment described herein, the configuration of the base canreduce the amount of dead space and be much more similar totraditionally used glass containers. For example, the substantially flatinner annular wall 240 can extend to a substantial outward extent towardthe edge of the container. By using a base configuration according tothe present invention, the inner diameter of the standing surface, i.e.the pushed-up region of the base D₁, as shown in FIG. 9, can be arelatively large portion of the container diameter D₂. According to thepresent invention, the ratio of the container diameter D₂ to thepushed-up diameter D₁ can be less than 1.5:1.0 and even 1.3:1.0 orlower. Stated differently, the diameter of the container D₂ can be lessthan 50% larger than, or as little as about 30% larger than, thediameter of D₁ of the pushed-up region. In cases where the container isnot round, this corresponds to a projected volume of the sidewall regionless than 70% greater than the projected area of the push-up region.

By way of example, and not by way of limitation, the container 200according to the present invention can have dimensions similar to thoseof the container 100. For example, the container can have a height ofabout 5.8 inches, an outermost diameter D₂ of about 3.8 inches, and cancontain a capacity of about 32 fluid ounces. The pushed-up region of thebase can have a diameter D₁ of about 3.1 inches. The brace 270 can havea brace ledge 276 that extends out about 0.6 inches from the dimple 248.The distance between opposite rib walls 274 can be about 1.2 inches,while the distance across the dimple 248 in the region between ribs canbe about 0.9 inches.

The containers 100 and 200 can be blow molded from an injection moldedpreform made from, for example, PET, PEN or blends thereof, or can beextrusion blow molded plastic, for example, polypropylene (PP). Inaddition, the containers 100 and 200 can be multilayered, including alayer of gas barrier material or a layer of scrap material. Resins alsoinclude polyester resins modified to improve UV resistance, for exampleHeatwave™ CF246, available from Voridian (Kingsport, Tenn., U.S.A.). Thefinishes of the containers can be injection molded, i.e. the threadedportion can be formed as part of the preform, or can be blow molded andsevered from an accommodation feature formed thereabove, as is known inthe art.

The above described containers 100 and 200 are capable of use, forinstance, in hot-fill operations having fill temperatures up to about205° F. As explained above, containers 100 and 200 having base 112 and212 can be utilized when processing temperatures approach or exceed 205°F. The containers can also be utilized in typical pasteurizationprocesses used in the packaging art. In an exemplary process, a coldsolid product, such as pickles, is combined with mildly heated brine at120 to 140° F. within the container. After the container is capped, thefilled container can be processed through a pasteurization tank, wheretemperatures approach about 212° F., so that the solid products in thesealed container are heated to approximately 175° F. for 15 minutesbefore the filled and sealed container is cooled to ambient temperature.

The present invention provides a container 10 which is particularlysuited for use as ajar for packaging food products. For example, thecontainer 10 can be used to package fluent or semi-fluent food productssuch as applesauce, spaghetti sauce, relishes, sauerkraut, baby foods,and the like. It can also be used to package a solid food productsuspended in a liquid brine, such as pickles. Thus, the container 10 canbe utilized for packaging various food products and can withstandvarious fill and treatment operations, as will be discussed.

As illustrated in FIG. 10, in one preferred embodiment of the presentinvention a container 10 is provided having a base 12, a substantiallycylindrical sidewall 14, and a wide-mouth threaded finish 16 whichprojects from the upper end of the sidewall 14 via a shoulder 18.Preferably, as illustrated, upper and lower label bumpers, 20 and 22,are located adjacent the shoulder 14 and base 12, respectfully, andoutline a substantially cylindrical label area 24 on the sidewall 14.Thus, a label (not shown) can be attached to, and extend completelyaround, the container sidewall 14. In addition, preferably the sidewall14 has a series of circumferential grooves 26 which reinforce thecylindrical shape of the sidewall 14 and resist paneling, dents andother unwanted deformation of the sidewall 14.

The container 10 is multi-functional since it can be utilized inhot-fill as well as pasteurization/retort processing. To accomplish thisobjective, the base 12 has a structure which is capable of accommodatingelevated internal container pressure experienced duringpasteurization/retort processing and which is capable of accommodatingreduced container volume experienced upon cool down of a filled andsealed container after hot-fill or pasteurization/retort processing. Tothis end, the base 12 flexes downwardly in a controlled manner and to adesired extent when pressure within the filled and sealed container iselevated, and the base 12 flexes upwardly in a controlled manner and toa desired extent when a vacuum develops within the filled and sealedcontainer.

Structurally, the base 12 includes a discontinuous concave outer annularwall 28 which provides a plurality of spaced-apart, arcuate supports 30adjacent the outer periphery 32 of the base 12. As illustrated, foursupports 30 are utilized in the preferred embodiment; however, three,five or more supports 30 could also be utilized. Each support 30 has anouter wall portion 34 which extends upwardly toward the lower labelbumper 22 and an inner wall portion 36 which extends upwardly andinwardly into the remaining base structure as will be discussed. Astanding surface 38 is formed at the juncture of each outer and innerwall portions, 34 and 36, thereby forming a discontinuous support ringof the container 10.

An inner annular wall 40 extends within the discontinuous concave outerannular wall 28 and is preferably slightly inclined relative to thehorizontal. Preferably, the inclined inner annular wall 40 extendsupwardly and inwardly at an angle “A” relative to the horizontal as itextends from its outer periphery 42 to its inner periphery 44. Forexample, the inner annular wall 40 can incline at an angle “A” in arange of about 5° to about 6° relative to a horizontal plane “P”extending through the standing surfaces 38. Alternatively, the innerannular wall 40 can be formed substantially planar and parallel to ahorizontal plane “P” extending through the standing surfaces 38.

The outer periphery 42 of the inner annular wall 40 merges with theinner wall portion 36 of each of the supports 30 and with a plurality ofspaced-apart, horizontally-disposed, radial webs 46 located adjacent theouter periphery 32 of the base 12. Each of the webs 46 extends betweenthe supports 30 and connects to the container sidewall 14 at anelevation above the horizontal plane “P” extending through the standingsurfaces 38. The inner periphery 44 of the inner annular wall 40 mergesinto an anti-inverting dome 48 which projects upwardly into thecontainer 10. Preferably, the inner annular wall 40 and anti-invertingdome 48 merge via an annular hinge 50. As illustrated in FIG. 13, theanti-inverting dome 48 has a conical lower portion 52 adjacent hinge 50and a convex upper portion 54.

The inner annular wall 40 functions as a flex panel. To this end, whenthe internal pressure increases within a filled and sealed container,the inner annular wall 40 flexes downwardly as shown in dashed lines “B”in FIG. 13 to accommodate the increased pressure and prevent thesidewall 14 of the container 10 from undergoing unwanted permanentdistortion. In addition, the inner annular wall 40 flexes upwardly torelieve vacuum when the contents of a hot filled and capped container,or a filled, capped and subsequently pasteurized container, cool toambient. This is shown in dashed lines “C” in FIG. 13. Thus, when thesealed container and contents cool to ambient, the sidewall 14 issubstantially cylindrical and unchanged from its as-formed shape and iscapable of neatly supporting a wrap-around label without unwanted voidsor the like beneath the label. In addition, the sidewall 14 resistsovalization and the base 12 provides a level seating surface which isnot subject to rocking or the like.

The anti-inverting dome 48, the supports 30 and the radial webs 46support the inner annular wall 40 and permit it to flex only within adesired range of movement as illustrated by dashed lines “B” and “C”.For instance, the inner annular wall 40 flexes downwardly due to anincrease in pressure within the container, but is prevented fromcomplete inversion and failure by the anti-inverting dome 48 whichtravels with the inner annular wall 40 but substantially maintains aconstant shape regardless of the internal pressure experienced withinthe container.

Another feature of the base 12 of the present invention is that eachinner wall portion 36 of the arcuate supports 30 has an arcuateshoulder, or support ridge, 56 formed therein and spaced in elevationfrom both the support surfaces 38 and the inner annular wall 40 tofacilitate vertical stacking of like containers 10. For example, asillustrated FIG. 14, an upper container 10 a is stacked on a lowercontainer 10 b. The support ridge 56 in the base 12 a of the uppercontainer 10 a seats on the outer edge 58 of the upper surface 60 of thelid 62 of the lower container 10 b such that the horizontal plane “Pa”extending through the standing surfaces 38 a of the upper container 10 aextends a spaced distance beneath the top surface 60 of the lid 62 ofthe lower container 10 b.

By way of example, and not by way of limitation, the container 10according to the present invention preferably has a height “H” of about5.8 inches, a container outermost diameter “D” of about 4.2 inches, andcontain a capacity of about 32 fluid ounces. The discontinuous standingring formed by the standing surfaces 38 has a diameter of about 3.6inches, and the inner annular wall 40 of the base 12 has an innerperiphery 44 with a diameter of about 1.6 inches and an outer periphery42 with a diameter of about 2.2 inches. The radial webs 46 are uniformlyspaced apart and separate each support 30 such that each support 30 isat least about 0.8 radians. In addition, each support 30 has a slightlylarger arcuate extent than that of each radial web 46.

Preferably, the container 10 is blow molded from an injection moldedpreform made of PET, PEN or blends thereof or is extrusion blow moldedof PP. In addition, the container 10 may be multilayered including alayer of gas barrier material or a layer of scrap material. Preferably,the finish 16 of the container is threaded, blow molded, and severedfrom an accommodation feature formed thereabove.

The above described container 10 is capable of use in hot-filloperations having fill temperatures up to 205° F. It can also beutilized in pasteurization processes wherein a cold solid product, suchas pickles, is combined within the container 10 with mildly heated brineat 120 to 140° F. After the container 10 is capped, the filled containercan be processed through a pasteurization tank where temperaturesapproach about 212° F. so that the solid products in the sealedcontainer are heated to approximately 175° F. for 15 minutes before thefilled and sealed container is cooled to ambient temperature.

While preferred containers and base structures have been described indetail, various modifications, alterations and changes may be madewithout departing from the spirit and scope of the present invention asdefined in the appended claims.

1. A method of processing a plastic container, comprising: (a) providinga plastic container having an upper portion including a finish, asidewall, a lower portion including a base defining a standing surface,and a substantially transversely-oriented pressure panel located in thebase; (b) introducing heated liquid contents into the plastic containerwith the pressure panel located in an inwardly-inclined positionentirely between the standing surface and the upper portion, with theincline of the pressure panel being defined from a direction from thestanding surface toward the central longitudinal axis of the plasticcontainer; (c) capping the plastic container; and after said step (c),(d) moving the pressure panel to an outwardly-inclined position entirelybetween the standing surface and the upper portion.
 2. The method ofclaim 1, further comprising the step of blow molding the plasticcontainer with the pressure panel in the inwardly-inclined position. 3.The method of claim 1, further comprising the step of cooling theplastic container and liquid contents after the step (d), said coolingcausing the pressure panel to move inwardly.
 4. The method of claim 1,wherein the step (d) occurs as a result of increasing internal pressurewithin the plastic container.
 5. The method of claim 1, wherein thepressure panel is operative to prevent inversion of the pressure paneland includes ribs radially extending therefrom, each said rib linearlytapering in plan view at a substantially constant rate oversubstantially its entire length.
 6. The method of claim 1, wherein saidstep (d) includes moving the pressure panel outwardly to theoutwardly-inclined position.
 7. The method of claim 1, wherein said step(d) includes moving the pressure panel from the inwardly-inclinedposition to the outwardly-inclined position.
 8. The method of claim 1,wherein the pressure panel includes a wall, the wall being radiallyinward of a hinge and circumscribed by the hinge.
 9. The method of claim8, wherein the wall is substantial flat.
 10. A method of processing aplastic container, comprising: providing a blow molded plastic containerhaving an upper portion including a finish, a sidewalk, a lower portionincluding a base defining a standing surface, and a substantiallytransversely-oriented pressure panel located in the base, the pressurepanel being blow molded in a first inwardly-inclined position entirelybetween the standing surface and the upper portion; introducing heatedliquid contents into the plastic container having the pressure panelinitially positioned in the first inwardly-inclined position; cappingthe plastic container; flexing the pressure panel downwardly to anoutwardly-inclined position entirely between the standing surface andthe upper portion when the container is filled, capped, and subjected toan increase in pressure inside the container; cooling the plasticcontainer and liquid contents; and after said cooling, moving thepressure panel from the outwardly inclined position to a secondinwardly-inclined position entirely between the standing surface and theupper portion to relieve vacuum when the contents of the tilled andcapped container are cooled, wherein said moving the pressure paneloccurs as a result of an internal vacuum formed within the plasticcontainer.
 11. The method of claim 10, wherein the firstinwardly-inclined position is different from the secondinwardly-inclined position.
 12. The method of claim 10, wherein thePressure panel has a frustum-shaped portion operative as ananti-inversion portion to prevent complete inversion of the pressurepanel, and wherein, for each of said fleeing and said moving, thefrustum-shaped portion maintains substantially a constant shape.
 13. Amethod of processing a plastic container, comprising: (a) providing aplastic container having an upper portion including a finish, asidewall, a lower portion including a base defining a standing surface,and a substantially transversely-oriented pressure panel located in thebase, and an anti-inverting central portion surrounded by the pressurepanel and opening downwardly in the base; (b) introducing heated liquidcontents into the plastic container having the pressure panel; (c)capping the plastic container; (d) cooling the plastic container andliquid contents; and (e) prior to said cooling, moving the pressurepanel between an outwardly-inclined position entirely between thestanding surface and the upper portion and an inwardly-inclined positionentirely between the standing surface and the upper portion, theanti-inverting central portion traveling up and down with thesurrounding pressure panel while remaining in the downwardly-openposition and maintaining a substantially constant shape, wherein saidmoving the pressure panel occurs as a result of an internal vacuumformed within the plastic container.
 14. The method of claim 13, furthercomprising the step of blow molding the plastic container with thepressure panel in the inwardly-inclined position.
 15. The method ofclaim 13, wherein the outwardly-inclined position and theinwardly-inclined position are maximum desired limits within which thepressure panel can move.
 16. The method of claim 13, wherein thepressure panel further includes a plurality of tapering ribs adjacentthe anti-inverting portion.
 17. The method of claim 13, wherein thepressure panel includes a wall and a plurality or ribs, the wall beingradially inward of a hinge and circumscribed by the hinge, and the ribsoriginating at an innermost radially inward portion of the wall, each ofthe ribs extending in a direction away from the wall.